Concentric tube heat exchanger with sintered metal matrix



June 6, 1967 F. A. BURNE ETAL CONCENTRIC TUBE HEAT EXCHANGER WITH SINTERED METAL MATRIX 3 Sheets-Sheet- 1 Filed 000. 14, 1964 FIG-2 INVENTORSI FREDERICK/4. BURNE RAGHUNA TH 1 DATE 6/ Muff ATTORNEY June 6, 1967 F. A. BURNE ETAL 3,323,586

CONCENTRIC TUBE HEAT EXCHANGER WITH SINTERED METAL MATRIX Filed Oct. 14, 1964 Sheets$heet- 2 INVENTORS. FREDER/CKA. BURNS RAGHUNATH V. DATE ATTOPNEV June 6, 1967 F. A. BURNE ETAL 3,323,586

CONCENTRIC TUBE HEAT EXCHANGER WITH SINTERED METAL MATRIX Sheets-Sheet Filed Oct. 14, 1964 NQN 4 mm M mw M A/Q W KH 167 mm 50 VI .DH W FR ?0 .Lli.

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ATTORNEY United States Patent 3,323,586 CONCENTRIC TUBE HEAT EXCHANGER WHTH SltlTrERED METAL MATREX Frederick A. Rome and Raghunath V. Date, New Haven,

Conn, assignors to Olin Matliieson Chemical Corporation, a corporation of Virginia Filed Oct. 14, 1964, Ser. No. 403,857 3 Claims. (Cl. l65154) This invention relates to heat exchangers, and more particularly to a heat exchanger having a body of pervious material therein.

As is known in the heat exchanger art, the greatest heat exchange is achieved by providing the maximum possible area of material across which the desired heat exchange may take place. Various devices have been employed to so increase the material area such as, for example, fins or corrugations across which pass the media between which the heat exchange is to take place. However, it has been found that greatly increased heat transfer surfaces can be achieved by instead employing a body of pervious material, or a porous body having interconnected voids. Such a body of pervious material presents a large number of faces for heat exchange purposes, as well as other advantages to be discussed shortly.

By the instant invention there is provided a unique configuration and arrangement of such a pervious body within a heat exchanger which has been tested and found to result in greatly increased heat exchange properties. The concept may be employed in heat exchangers of any desired shape, but is particularly adapted to tubular heat exchangers. As known in the art, the use of heat exchangers of a tubular configuration is highly advantageous in certain environments where the exchanger is so situated that it is immersed in one of the heat exchange media. The tubular heat exchangers presently in use in such an environment commonly comprise two concentric tubes, often with corrugations in the annulus between the tubes to turbulate the circulated medium; the flow path in the annulus is substantially axial along the tubes.

In the concept of the instant invention there is provided a heat exchanger in which not only the heat exchange area is increased but the medium flow is directed in a peripheral path through the annulus formed by the concentric tubes. The advantages resulting are achieved by the provision of a body of pervious material in the space between the tubes. By a particular configuration and arrangement of the pervious body to be discussed hereinafter, channels are provided to serve as inlet and outlet means for a heat exchange medium and to permit uniform distribution of the medium through the pervious material in a peripheral path through the annulus.

While the usual expedient is to arrange the tubes so as to be concentric, the concept of this invention is equally applicable to any arrangement of a tube or tubes within a tube.

As will be understood, various combinations of metals may be utilized in forming the heat exchangers according to the instant invention; and accordingly the solid portions and the pervious body may be of the same metal or alloy, or the pervious structure and the solid member may be comprised of different compositions. For example, both the pervious body and solid portions may be formed of the same stainless steels, coppers, brass, carbon steels, aluminums or various combinations thereof. As will be evident, the ultimate use of the resultant structure determines the specific combination of alloys to be employed. The production of the pervious body is most flexible; for example, it may be produced by a process wherein particles, frequently spherical, are poured by gravity into an appropriately shaped confined space and usually vibrated to cause the particles to compact uniformly. As is ice obvious, the choice of particle size will largely determine the size of openings of the resulting pervious body. The body of particles so packed is then treated in accordance with any of the well known metallurgy practices e.g. sinterin'g, welding, brazing or soldering employing an appropriate coatingto produce a metallic bond between the particles. Thus, there is provided a pervious body whose bulk density, or apparent density, is but a fraction of the density of the metal or alloy from which the particles are obtained. Furthermore, such process results in a metallic bond between the pervious body and its container.

While the above described process is perferred in the instant invention, other processes may be employed. For example, it is possible to blend intimately a particulate material with either a combustible substance or a soluble material whose melting point exceeds the melting temperature of the particulate material. After the blend is compacted and treated to achieve a metallic bond, the combustible substance may be burned away or the soluble material removed by leaching or dissolving with a liquid. A still further method of producing the pervious body comprises melting a metal or alloy and casting it into the interstices of a loose aggregate of a. particulate soluble material whose melting point exceeds that of the metal, preferably having a specific gravity of the molten metal. Upon solidification of the metal, a component is produced which contains the network of the soluble material interspersed within the solid metal which. soluble material is thereupon removed by leaching or dissolving, leaving behind it interstices that interconnect and form a pervious network within the resultant metal body. A still further method of producing such pervious bodies comprises weaving of knitting metal wire into a mesh arranged in a plurality of layers. According to this process, a control of porosity is obtained by appropriate choice of wire diameters and openings arranged between adjoining wires as well as the juxtapositioning of superimposed layers of the woven or knit mesh.

It is to be understood that the concept of this invention need not be limited to the particular configuration indicated above. For example, tubes need not be exclusively employed; any desired shape of exchanger may be provided, with the pervious body shaped accordingly to fit. Furthermore, any number of tubes may be employed, the exchanger may be used for either heating or cooling, and the tubes may be of any desired cross-section.

It is accordingly an object of this invention to provide a heat exchanger which is compact and yet capable of high elficiency and low pressure drop.

It is a further object of this invention to provide such a heat exchanger having a body of pervious material situated therein.

It is a still further object to provide such a heat exchanger of concentric tubular members having a body of pervious material bonded within the annulus between the tubular members.

Other objects and advantages will become apparent to those skilled in the art from a consideration of the details of several specific embodiments illustrated in the drawings, in which:

FIGURE 1 is a perspective view of a first embodiment of heat exchanger contemplated in this invention,

FIGURE 2 is a longitudinal crosssection of the embodiment of FIGURE 1, taken along the lines 11-11 thereof,

FIGURE 3 is an axial cross-section of the embodiment of FIGURE 1 taken along the lines III-III thereof,

FIGURE 4 is a perspective view of a second embodiment of this invention,

FIGURE 5 is a longitudinal cross-section of the em- 3 bodiment of FIGURE 4 taken along the lines V-V thereof,

FIGURE 6 is an axial cross-section of the embodiment of FIGURE 4 taken along the lines VI-VI thereof, and

FIGURE 7 is a schematic view of an assembly embodying a plurality of heat exchangers according to this invention.

A first embodiment of heat exchanger employing the concept of this invention is shown in FIGURE 1, and is designated generally by 10. As indicated hereinbefore, the heat exchanger 10 is to be employed in applications where it is immersed in one of the heat exchange media. Thus, a first heat exchange medium, for example that to be employed in heating or cooling, surrounds the heat exchanger 10 and is also introduced into the heat exchanger 10 at one end, as shown by the arrow 11, and exits from the opposite end of the heat exchanger 10 as shown by the arrow 12. Obviously, required fittings, not shown, may be employed. A second heat exchange medium, for example the medium to be cooled or heated, enters the heat exchanger 10 through any suitable fitting in the direction of the arrow 13, is circulated through the heat exchanger, and exits through a suitable fitting in the direction of the arrow 14. Thus, heat exchange may take place between the second medium and (a) the first medium surrounding the exchanger, and (b) the first medium flowing through the heat exchanger. It will be obvious that any desired mediums might be employed in the instant heat exchanger; for example, in application in an automotive cooling system, the medium introduced at 11 may be water and the medium introduced at 13 may be oil.

The construction of the heat exchanger 145 is shown in detail in FIGURES 2 and 3, wherein it may be seen that the heat exchanger 10 comprises two concentric tubes 15 and 16 having therebetween a body of pervious material 20. Suitable inlet and outlet fittings 18 and 19 are provided at opposite ends of the heat exchanger. The annulus between tubes 15 and 16 is closed off at its opposite ends, for example by annular seals 17. Whatever method of producing the pervious body 20 is employed, the body 2G is formed so that there exists two channels 21 and 22 spaced 180 apart, for example as shown in FIG- URE 3, to form the body 20. These channels may be achieved, for example, by providing in the concentric tubes 15 and 16 two appropriately shaped cores prior to the addition of the porous material 20. Following the required subsequent processing of the material 20, the coreswhich are shaped the same as the desired channels 21 and 22 may be removed. It will be evident that the pervious body 20 will be securely bonded to the tubes 15,

16, and that channel 21 communicates with the inlet 18, and the channel 22 with the outlet 19. Thus, the medium introduced at the inlet 18 flows through the channel 21 and distributes uniformly along the length of tube 16,

thence around the tube 16 as shown by the arrows 23 of FIGURE 3 through the circuitous paths within the pervious material 20 to the lower channel 22, where it may pass through the outlet 19. It will be evident that the provision of the pervious body 20 not only presents increased heat exchange surfaces for contact by the circulated medium but, due to the circuitous peripheral flow paths presented, also provides uniform distribution through the entire pervious structure with a minimum pressure drop.

A second modification of the instant invention is depicted in FIGURES 46. In this embodiment, there is provided an appropriate manifold so that the exchanger may be employed in applications where it is desirable that the inlet and outlet be on the same side of the exchanger. As was the case with the exchanger of FIGURES l3, the heat exchanger 110 is immersed in a first heat exchange medium, which enters the exchanger in the direction of the arrow 111 of FIGURE 4, and exits at the opposite end as shown by the arrow 112. However, in this embodiment, the second medium may enter and exit from the same side of the exchanger, as shown at 113 and 114.

Referring now to FIGURES 5 and 6, it will be evident that the tubes and 116, the annular seals 117, and the pervious body having channels 121 and 122 are analogous to the structure of the first embodiment referenced by the respective characters, 15, 14-5, 17, Ed, 21, and 22. However, the inlet 118 and outlet 119 are situated on the same side of the heat exchanger 11%. A manifold is provided near the outlet 119 comprising a ring 123 surrounding the inner tube 116 and having a peripheral flange 12 The flange 124 covers the entire annulus between the tubes 116 and 115 except for an area in alignment with and matching the configuration of the channel 122. Thus, it will be seen that the second medium, e.g., that to be heated or cooled, enters through the fitting at 118 and distributes uniformly along the length of the tube 116 within the channel 121, thence around the tube 116 as shown by the arrows 125 of FIGURE 6, through the circuitous paths provided in the pervious body 12%, collecting in the channel 122, from which it is forced within the annulus 125 between the ring 123 and tube 115 from the lower portion thereof to the upper portion thereof, where it exits through the fitting provided at 119. The flange 1224 prevents such medium from entering the ring 123 except at the desired point, that is, at the lower portion thereof through the channel 122.

The second embodiment of this invention may be fabricated in the same manner as that indicated hereinbefore with respect to the first embodiment.

in FIGURE 7 there is illustrated the adaptability of the heat exchanger of the present invention to an installation requiring a plurality of heat exchangers. Thus, the heat exchanger of the instant invention may be employed where one or both of the heat exchange media is desired to be in either series or parallel flow, or any combination thereof. As shown schematically in FIGURE 7, either of the heat exchangers It or 11% may be provided with appropriate conduits, not shown, to achieve the desired flow. For example, a heat exchange medium may take the central path through the exchangers as shown by the solid arrows 212 in serial flow through any number of heat exchangers 110 and/or in parallel flow through any number of exchangers 10. It will be understood first that by appropriate conduit arrangement the heat exchangers it? and 110 may be interchanged, and secondly, that the flow of the second heat exchange medium in the peripheral path may be in the conventional manner through each of the exchangers as a separate unit.

Or, if so desired, the second heat exchange medium may be in series and/or parallel fiow through the peripheral path of each of the heat exchangers, with the first medium in series and/or parallel flow or in the conventional manner through each of the heat exchangers as a separate unit. Thus, as shown by the dotted arrows 213, series fiow may be accomplished through a number of heat exchangers 119 and/or parallel flow through a number of heat exchangers 10.

While We have shown and described different desirable embodiments of this invention, it is to be understood as for the purpose of illustration only and that various changes and modifications, as well as the substitution of equivalent elements for those herein shown and described, may be made Without departing from the spirit and scope of the invention as set forth in the appended claims.

We claim:

1. A heat exchanger for circulation of a plurality of heat exchange media comprising A. a first conduit means for conveying a first heat exchange medium,

B. a second conduit means surrounding said first conduit means for conveying a second medium in the space between said first and second conduit means,

C. a body of pervious material in said space between said first and second conduits and in heat exchange relationship with said first and second conduit means, said body of pervious material being joined by a metallic bond to said first and second conduit means and including (1) a first channel for controlled distribution of said second medium entering the heat exchanger, (2) a second channel for controlled collection of said second medium leaving the heat exchanger, said second channel being spaced from said first channel, and D. manifold means within said space between said first and second conduits sealing one end of said first channel and in open communication with said second channel for receiving the flow of said second heat exchange medium from said second channel such that the second medium flows from said first channel circumferentially through the pervious material to said second channel, and E. inlet and outlet means in said second conduit. 2. A heat exchanger in accordance with claim 1 wherein said manifold means comprises a ring surrounding said first conduit means and having a flange extending throughout said space between said first and second conduit means, said flange having an aperture in communication with said second channel.

3. A heat exchanger in accordance with claim 2 having inlet means in said second conduit means in communication with said first channel, outlet means in said second conduit means spaced from said second channel, said manifold means joining said second channel to said outlet means.

References Cited UNITED STATES PATENTS 2,448,315 8/1948 Kunzog l65154 X 2,893,703 7/1959 Richardson 165-47 FOREIGN PATENTS 133,579 8/ 1929 Switzerland.

ROBERT A. OLEARY, Primary Examiner. A. W. DAVIS, Assistant Examiner. 

1. A HEAT EXCHANGER FOR CIRCULATION OF A PLURALITY OF HEAT EXCHANGE MEDIA COMPRISING A. A FIRST CONDUIT MEANS FOR CONVEYING A FIRST HEAT EXCHANGE MEDIUM, B. A SECOND CONDUIT MEANS SURROUNDING SAID FIRST CONDUIT MEANS FOR CONVEYING A SECOND MEDIUM IN THE SPACE BETWEEN SAID FIRST AND SECOND CONDUIT MEANS, C. A BODY OF PERVIOUS MATERIAL IN SAID SPACE BETWEEN SAID FIRST AND SECOND CONDUITS AND IN HEAT EXCHANGE RELATIONSHIP WITH SAID FIRST AND SECOND CONDUIT MEANS, SAID BODY OF PERVIOUS MATERIAL BEING JOINED BY A METALLIC BOND TO SAID FIRST AND SECOND CONDUIT MEANS AND INCLUDING (1) A FIRST CHANNEL FOR CONTROLLED DISTRIBUTION OF SAID SECOND MEDIUM ENTERING THE HEAT EXCHANGER, (2) A SECOND CHANNEL FOR CONTROLLED COLLECTION OF SAID SECOND MEDIUM LEAVING THE HEAT EXCHANGER, SAID SECOND CHANNEL BEING SPACED FROM SAID FIRST CHANNEL, AND 